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United States Patent |
5,088,336
|
Rosenberg
,   et al.
|
*
February 18, 1992
|
Pipeline caliper pig
Abstract
An improved pipeline caliper pig for providing a record of the deviations
of the interior wall of a pipeline including a pig body assembly having a
longitudinal axis and support members so that the pig body assembly is
supported within a pipeline, the support members impeding the flow of
fluid therepast so that the pig body is propelled by fluid flow along the
interior of the pipeline, an integrator plate carried by the pig body
assembly, arms extending from the pig body assembly for responding to
deviations in the interior wall of the pipeline and coupling members to
transfer the deviations to the integrator plate, a plurality of axially
positionable shafts affixed at one end of the integrator plate, and
electrical transducers at the other end of each shaft so that movement of
the integrator plate relative to the pig body is transmitted into
electrical signals, an orientation detection member and a signal receiver
and recorder to record the electrical signals of the transducers and the
orientation detection member so that deviations in the interior wall of
the pipeline and the orientations of such deviations relative to the
vertical are recorded as electrical signals, the recorded signals being
recoverable whereby the pipeline operator can be advised to the conditions
of the inside wall of a pipeline through which the caliper pig has passed.
An alternate embodiment includes the use of three odometer wheels
producing electrical signals responsive to the rotation thereof providing
indications of curves, bends, dips and rises in the pipeline.
Inventors:
|
Rosenberg; Jeffrey S. (Tulsa, OK);
Lockyear; Kevin W. (Tulsa, OK)
|
Assignee:
|
TDW Delaware, Inc. (Tulsa, OK)
|
[*] Notice: |
The portion of the term of this patent subsequent to September 4, 2007
has been disclaimed. |
Appl. No.:
|
711368 |
Filed:
|
June 5, 1991 |
Current U.S. Class: |
73/865.8; 33/544 |
Intern'l Class: |
G01B 005/00 |
Field of Search: |
73/855.8,866.5,432.1
33/302,544,777,1 H,342
|
References Cited
U.S. Patent Documents
2619728 | Dec., 1952 | Ely | 33/1.
|
2834113 | May., 1958 | En Dean et al. | 73/40.
|
3755908 | Sep., 1973 | Ver Nooy | 33/542.
|
3882606 | May., 1975 | Kuenel et al. | 33/544.
|
4524526 | Jun., 1985 | Levine | 33/302.
|
4930223 | Jun., 1990 | Smith | 33/777.
|
Primary Examiner: Noland; Tom
Attorney, Agent or Firm: Head & Johnson
Parent Case Text
This application is a continuation of 07/545,054 filed June 28, 1990 now
abandoned which was a continuation of 06/822,755 filed Jan. 17, 1986 and
now U.S. Pat. No. 4,953,412.
Claims
What is claimed is:
1. A pipeline caliper pig for providing information about an indentation in
the inner wall of a pipeline, comprising:
a pig body assembly having a longitudinal axis and having means for support
thereof in a pipeline and for impeding the flow of fluid therepast so that
the pig body is propelled by such fluid flow along the interior of the
pipeline, the pig body being subject to at least limited rotation about
its longitudinal axis as it is propelled along the interior of a pipeline;
means carried by said pig body for measuring indentations in the internal
pipeline wall;
means for indicating the axial orientation of said measured pipe wall
indentation relative to said pig body;
means for detecting the axial orientation of said pig body about its
longitudinal axis relative to the vertical;
means employing said measuring means, said indicating means and said
detecting means to determine the axial orientation of said internal pipe
wall indentation relative to the vertical; and
means carried by said pig body for recording said detected pipeline wall
indentation and said axial orientation thereof.
2. A pipeline caliper pig according to claim 1 including:
odometer means carried by said pig body having means to engage the pipeline
interior wall; and
means for recording distance measurements of said odometer means and
correlating such distance measurements to the measurements of indentation
to said pipewall.
Description
BACKGROUND AND SUMMARY OF THE INVENTION
During installation of pipelines they can often be dented or buckled as a
result of construction activity, such as during the backfilling the ditch
in which they are laid and so forth. After pipelines have been installed
they still are subject to becoming damaged due to the effect of
temperature changes causing stretching and buckling, freezing and thawing
of the earth, shifting in the earth's structure, damage from other
construction activities, and so forth. In addition, debris can gather in
certain areas in a pipeline forming an obstruction to the flow of fluid
therethrough. For these and other reasons, a technique which has been
employed in the pipeline industry to determine the character of the
internal pipeline wall is to pass a caliper pig through the pipeline. The
caliper pig was invented by Burton VerNooy, patentee of U.S. Pat. No.
3,755,906 entitled "Pipeline Pig". The pipeline pig of the VerNooy
invention includes a body assembly with spaced apart cups affixed to the
body. The cups form the dual function of supporting the body in the
pipeline and at least one of the cups interfere with the fluid flow
through the pipeline so that the pig is carried along by the fluid flow.
Attached to the body are a plurality of arms which extend out to engage
the interior of the rearward cup. Coupling members extend from the arms to
an integrator plate which is attached to an axially positionable central
shaft. Within the pig body is an instrument package providing a moving
chart. A pen stylus is affixed to the inner end of the shaft.
As the pipeline pig of the VerNooy patent passes through a pipeline and
encounters a deflection of the inner pipeline wall, the cup is deformed
and thereby one or more of the finger mechanisms is deflected. This
deflection is transmitted to the integrator plate which causes the axial
shaft to be displaced. The shaft displacement is indicated on the chart.
By means of an odometer system the chart is moved in proportion to the
travel of the pig through the pipeline so that after the chart has been
recovered following a complete run of a pig, the extent of and the
location of a deviation in the pipeline wall is indicated.
While the pipeline pig of U.S. Pat. No. 3,755,908 works exceedingly well
and has proven to be a great boom to the operators of pipelines in the
United States and many parts of the world, nevertheless, it has some
deficiencies. A primary deficiency of the pipeline pig as disclosed in
U.S. Pat. No. 3,755,908 is that when an anomoly in the interior wall of a
pipeline is detected it is recorded in the same manner on the chart
regardless of the axial orientation of the anomoly. For instance, if an
interior protrusion occurs in a pipeline it will be indicated and the
depth of the protrusion and its location along the length of the pipeline
will be indicated; however, the axial orientation is not indicated, that
is, whether the indentation is at the top, bottom or sides of the pipeline
is not known to the operator. Further, the moving paper chart must move at
a relatively slow rate to permit a pipeline pig to travel several miles
within a pipeline, therefore, the characteristics of anomolies which are
detected can not be easily determined from the paper chart.
The present invention overcomes these problems associated with the
presently known caliper pigs represented by U.S. Pat. No. 3,755,908. The
invention provides an improved caliper pig, which, among other advantages,
produces a rotationally oriented signal detection system so that the
record provides not only the location and depth of a protrusion, as an
example, but also the axial orientation thereof relative to the vertical.
In addition, means is provided for greatly improving the quality of the
records so that more information is provided as to the size and shape of
any anomoly detected in the interior pipeline wall.
To accomplish these goals the present invention includes a pig body
assembly having a longitudinal axis. Means is provided in the form of
spaced apart cups of resilient material for supporting the pig body within
the pipeline. At least one of the cups is impervious to fluid flow, that
is, impedes fluid flow so that the pig is moved through the pipeline
interior by the flow of fluid. Contained within the body assembly is a
closed instrument package and batteries.
Affixed to the pig body assembly in conjunction with the rearward most
resilient cup is an integrator plate. Extending from the integrator body
assembly are a plurality of spaced apart fingers, each hinged at its inner
end to the pig body assembly. The outer ends engaging the cup to thereby
deflect in conformity with the deflection of the cup. The movement of the
fingers are each individually conveyed to the integrator plate by means of
coupling members extending from the fingers to the periphery of the
integrator plate.
At least three shafts are connected to the integrator plate, the axis of
each of the shafts being parallel to the longitudinal axis of the pig body
assembly. In the preferred arrangement one of the shafts is a central
shaft, the axis of which is coincident with the body longitudinal axis
with the other two shafts being spaced from the central shaft and spaced
from each other, such as 120.degree. apart, as an example.
Affixed to the inner end of each of the shafts is an electrical transducer,
that is, an element which transforms the axial displacement of each of the
shafts into an electrical signal. This is accomplished by means of a
rotary potentiometer each having a short shaft extending therefrom with a
crank arm extending from it. Each of the shafts connected to the
integrator plate are provided with a follower which engages a
potentiometer crank arm. As the integrator plate is pivoted in response to
changes in the internal configuration of a pipeline wall the displacement
of the shafts are transformed into electrical signals.
An odometer system is employed to provide a signal in response to the
movement of the pig through the pipeline. The odometer system preferably
employs two odometer wheels each of which provides an electrical signal
indicating its rotation, the odometer wheels being resiliently biased
against the interior of the pipeline. The signals are fed to an instrument
package which also receives the signals from the transducers connected to
the shafts extending from the integrator plate. In addition, a
gravitationally sensitive indicator is carried by the body assembly and
provides electrical signals indicating the orientation of the pig body
relative to the vertical. The orientation signals when coordinated with
the signals produced by the three shafts extending from the integrator
plate provide means of indicating the position relative to the vertical of
an internal deflection of the pipeline wall while the signals provided by
the odometer system identifies the position of the internal deflection
relative to the length of the pipeline.
An alternate embodiment of the invention provides means for detecting and
recording changes in the direction of a pipeline, such as curves, bends,
dips and rises. For this purpose three or more odometer wheels are secured
to the pig body assembly arranged in a common plane perpendicular to the
body assembly longitudinal axis and spaced in equal angular relationship.
When three odometer wheels are employed they are spaced 120.degree. apart.
Each odometer wheel includes a means of producing an electrical signal
indicative of the rotation of the wheel, such as one pulse per revolution.
These signals are fed to the electronic package where the signals are
stored along with the other signals, such as those from the orientation
card. Upon completion of a run of the pig the recorded signals may be
employed in a computer, utilizing an appropriate program, to provide a
record of the changes in direction of the pipeline, which changes can be
coordinated with the detected changes in orientation of the pig relative
to the vertical so that the final record will reveal curves to the left or
right or inclines or decline of the pipeline. Such detected changes in
direction of a pipeline when coordinated with recorded distance measuring
odometer signals help to more precisely identify the location of a
detected deviation in the pipeline wall so that the operator will know
more precisely where to uncover the pipeline for external visual
inspection of a problem area.
More details of the invention will be set forth in the attached description
and claims, including the attached drawings.
DESCRIPTION OF THE DRAWING
FIG. 1 is an elevational view of one embodiment of the improved pipeline
caliper pig of this invention shown mounted inside of a pipeline as it
would appear in use.
FIG. 2 is a cross-sectional view taken along the line 2--2 of FIG. 1.
FIG. 3 is a cross-sectional view taken along the line 3--3 of FIG. 2 and
showing more details of the means by which internal deviations in the
interior wall of a pipeline are converted into electrical signals.
FIG. 4 is a cross-sectional view taken along the line 4--4 of FIG. 2
showing essentially the same mechanisms as is revealed in FIG. 3 but from
a slightly different orientation.
FIG. 5 is a cross-sectional view taken along the line 5--5 of FIG. 3, the
view being taken through the body assembly and looking rearwardly towards
the rearward cup.
FIG. 6 is a cross-sectional view taken along the line 6--6 of FIG. 3
showing more details of a mechanism for providing axial orientation
signals so that the position of the occurrence of an anomoly in the
pipeline relative to the vertical can be determined from the record
provided by a complete caliper pig run.
FIG. 7 is an enlarged fragmentary view of the rearward portion of the
improved caliper pig showing one means of mounting the odometer wheels as
utilized to provide distance measurement signals.
FIG. 8 is a cross-sectional view taken along line 8--8 of FIG. 7 and
showing further details of the odometer wheel arrangement.
FIG. 9 is an elevational end view of the caliper pig showing an alternate
embodiment employing three odometer wheels and providing means of
detecting a bend or curve in the pipeline being traversed by the pig.
FIG. 10 is a fragmentary cross-sectional view of the rear portion of the
alternate embodiment of the caliper pig taken along the line 10--10 of
FIG. 9.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawings and first to FIG. 1 the improved caliper pig of
this invention is shown in elevational view within the interior of a
pipeline, the pipeline being indicated by the numeral 10. The caliper pig
includes a longitudinal pig body assembly generally indicated by the
numeral 12 with a forward cup 14 and a rearward cup 16. The cups support
the pig body assembly 12 centrally within the pipeline 10. One of the
cups, and preferably forward cup 14, is impervious to fluid flow so that
when the pig is inserted in a pipeline the flow of fluid moves the pig
through it. Rearward cup 16 may be impervious to fluid flow or may have
holes 18 therein as illustrated so as to balance pressure across the
rearward cup and to allow the force of fluid flow to be applied entirely
against the forward cup 16.
The pig includes an electronics package indicated in dotted outline and
identified by the numeral 20 which consists of circuit boards having the
necessary electrical items for processing electrical signals, including an
electronic clock. The electronics package includes circuits for treating
electrical signals and for storage of information for subsequent use.
While the electronics 20 may include a variety of different ways of
handling and storing the electrical signals necessary to provide a report
as to the characteristics of the interior of the pipeline 10 through which
the pig has passed, the preferred arrangement includes the use of digital
signal handling capabilities in which the information is stored in solid
state memory. Batteries 22 provide the electrical energy for the operation
of the electronics 20. The pig body assembly 12 includes a sealed housing
24 which, when secured in place on the pig body assembly, protects
electronics 20 and batteries 22 from the fluid or gas content of the
interior of pipeline 10.
Extending rearwardly from the pig body assembly is a subframe 26 which
supports arms 28A and 28B which have odometer wheels 30A and 30B rotatably
positioned at the outer ends thereof. The function of the odometer wheels
30A and 30B is to provide a signal utilized by electronics 20 to indicate
on the record the distance the pig has traveled through pipeline 10.
Referring to FIGS. 2, 3 and 4 more details of the improved caliper pig are
shown. The pig body assembly includes an inner rear plate 32 which
sealably receives the housing 24. Attached to the rearward surface of the
inner plate 32 is an outer rear plate 34. The rearward cup 16 is secured
between plates 32 and 34. The rearward cup extends out to a peripheral
edge 16A which engages the interior wall of the pipeline 10 and responds
to changes in the configuration of the pipeline interior wall, such as
dents, buckles, bulges, branch openings, debris, etc.
Affixed to the rearward surface of the outer rear plate 34 are boss members
36, each of which pivotally receives the inner end of a finger element 38.
As is seen in FIG. 2 each of the finger elements 38 is formed of parallel
portions and each has at the outer end a short length transverse member
40.
FIG. 2 shows in detail only two of the finger mechanisms 38, it being
understood that in the embodiment shown twelve are employed, spaced
30.degree. apart. A greater or a smaller number may be used, depending
somewhat on the diameter of cup 16 which, of course, is determined by the
size of the pipeline in which the pig is to be used. Whether an odd or
even number of finger mechanisms 38 are employed is irrelevant.
Supported rearwardly of the outer rear plate 34 is an integrator plate 42.
Attached to the integrator plate forward surface is a short stub shaft 44
for each of the fingers 38. A linkage 46 pivotally connects each finger 38
with a stub shaft 44. The inner end of each linkage is pivoted around a
bolt 48 to a mid-point on each of the fingers 38. At the opposite end of
each linkage 46 is pivot connection 50 by which each linkage is connected
to a stub shaft 44.
Four brackets 52 are affixed to the rearward surface of the outer rear
plate 34 and in like manner four brackets 54 are affixed to the forward
surface of the integrator plate 42. Extending between brackets 52 and 54
are four coiled springs 56 which urge the integrator plate towards the pig
body assembly and thereby, through linkages 46, urge the fingers 38
outwardly against the interior of rearward cup 16. Thus, the position of
the integrator plate 42 is determined by the cup 16. As the pig travels
through a pipeline the external peripheral edge of the cup conforms to the
interior configuration of the pipeline and as it changes contour this
change is transmitted through the fingers 38 and linkages 46 to integrator
plate 42.
Secured to the outer rear plate 34 is a tubular member 58 having an
interior bushing 60 in the outer end. Threadably positioned in the inner
rear plate 32 is another bushing 62. Slidably received in bushings 60 and
62 is a central shaft 64. At the rearward end of the central shaft is a
universal coupling 66 connected to a stub shaft 68 affixed to the
integrator plate rearward surface by a bolt 68A. Bushing 62 has seals
therein so that the central shaft 64 may be axially displaced while
maintaining the interior of housing 24 free from the liquids or gases
contained in pipeline 10. Extending sealably through rear plates 32 and 34
are two peripheral shafts 70 and 72 (See FIGS. 4 and 5), each of which is
parallel to the central shaft 64. At the rearward end of each peripheral
shaft 70 and 72 is a universal coupling 74 connecting to an extension
shaft 78. At the outer end of each extension shaft 78 is a second coupling
80. By means of stub shafts 81 the couplings 80 are connected to the
forward surface of the integrator plate 42 adjacent the periphery thereof.
(Only one of each of items 74, 78, 80 and 81 are seen). Each of the stub
shafts 81 is held in place by bolt 81A. The peripheral shafts 70 and 72
are preferably spaced apart from each other 120.degree. in a plane taken
perpendicular the longitudinal axis of the pig body assembly 12 which is
coincident with the axis of central shaft 64.
The function of central shaft 64 and peripheral shafts 70 and 72 is to
provide a means for axial oriented detection of the movement of integrator
plate 42 which in turn is responsive to deflections in the rearward cup
16.
Within housing 24 and forwardly of the inner rear plate 32 are three
electrical transducer elements 82, 84 and 86 associated respectively with
central shaft 64 and peripheral shafts 70 and 72. (See FIGS. 3 and 5.)
Each of the transducer elements has a rotary shaft extending therefrom
indicated by the numerals 82A, 84A and 86A. Affixed to rotary shaft 84A is
arm 90, to rotary shaft 86A is arm 92 and to rotary shaft 82A is arm 94.
As shown in FIG. 3, arm 90 (which is typically also of arms 92 and 94) has
a slot therein indicated by 90A. Affixed to central shaft 64 is a block 96
having a pin 96A extending therefrom, the pin being received in the slot
90A of the arm 90. In like manner, blocks 98 and 100 are affixed
respectively to peripheral shafts 70 and 72 with pins 98A and 100A
extending therefrom. Thus, the displacement of the integrator plate 42
displaces central shaft 64 and peripheral shafts 70 and 72 and this
displacement is transmitted to arms 90, 92 and 94 and thereby to the
transducer elements 82, 84 and 86. The transducer elements 82, 84 and 86
may be such as potentiometers providing a variable resistance in response
to the position of rotary shafts 82A, 84A, and 86A, which in turn is
indicative of the attitude of the integrator plate. Thus, means is
provided to transform the position of the periphery of cup 16 into
electrical signals. By the use of analog-to-digital converters in the
electronic package 20 the signals from the transducer elements 82, 84 and
86 are converter into digital signals. By the use of the three shafts 64,
70 and 72 the electrical signals provide indications not only of the
extent of deflection of the cup but also the rotational position of the
deflection relative to the pig body assembly.
Means for axially oriented detection of the movement of the integrator
plate 42 relative to the pig body assembly is achieved by the use of the
three shafts and three transducers. However, the caliper pig may, and in
fact experience with other types of pipeline pigs indicate that it will
assuredly tend to rotate out of a preselected orientation relative to the
vertical as it travels through a pipeline. The means for axial oriented
detection of anomolies in the pipe wall relative to the pig body assembly,
as heretofore described, will not tell an operator reviewing a read out
obtained from the recorded signals where such anomoly occurs in the
pipeline relative to the vertical. Since this information is important to
a pipeline operator, the present invention provides means of supplying
this information. Positioned within housing 24, as best seen in FIGS. 3
and 6, is an orientation card generally indicated by the numerals 102.
Mounted on the orientation card are a plurality of mercury switches 104,
nine being shown. Each of the mercury switches includes a small,
non-conductive tube, such as of glass or plastic, and a pool of mercury in
each tube which responds to gravity. As each switch is tilted mercury
flows toward one end of other of the tube and by means of conductors
within the tube the pool of mercury provides ON-OFF indication of its
location; that is, an indication of the tilt of each switch is provided.
By means of conductors (not shown) extending from the mercury switches 104
to the electronic package 20 signals provide an indication of the
orientation of the pig body assembly relative to the vertical.
By utilization of an odd number of equal angularly spaced mercury switches
as shown in FIG. 6, rather than an even number, the treatment of the
switch locations to indicate orientation relative to the vertical is more
easily accomplished since in all instances there will be an uneven number
of switches in opposite positions, that is, as in the orientation of FIG.
6, five switches have the mercury pool towards the inner end of the switch
and four have the mercury pool towards the outer end of the switch. The
mercury switches are oriented 40.degree. apart, however, since there is an
odd number, a change in orientation of 20.degree. will produce a change in
the combination of the switch positions. Thus, the orientation signaling
system of the type represented by FIG. 6 is accurate within 20.degree. of
the orientation of the pipeline pig relative to vertical. By use of an odd
number of equal ansularly spaced apart switches the orientation resolution
of the system is significantly improved which would be achieved if an even
number was used only by greatly increasing the number of switches.
In order to provide a pipeline operator with a meaningful report as a
result of the run of the caliper pig through a pipeline, the position in
the pipeline where anomolies occur must be accurately revealed by the
finished record. For this reason an odometer system is employed. As shown
is FIGS. 1 and 3, extending rearwardly from the rear plates 32 and 34 are
four rods 106. As seen in FIG. 2, the integrator plate 42 has large
openings 108 therein which permit the rods 106 to pass through without
interfering with the movement of the integrator plate. Supported at the
rearward end of the rods 106 is a subframe plate 26 as previously
identified. Extending rearwardly from the subframe plate 26 are two
brackets 110 (See FIGS. 1, 7 and 8) which support a pin 112 therebetween.
A hinge member 114 is received on the pin 102 and is free to pivot about
the pin. The hinge member 114 has a plate 116 extending from it. Two arms
118 and 120 are pivoted to plate 116 about a bolt 122. At the outer end of
each of the arms 118 and 120 in an odometer wheel 124 and 126,
respectively. The odometer wheels 124 and 126 engage the interior of pipe
10 on opposite internal circumfertial surfaces thereof so that as the
caliper pig travels through a pipeline the wheels 124 and 126 accurately
measure the distance traveled.
To detect the revolution of odometer wheels 124 and 126 each is provided
with a magnet 128. Supported on the arms 118 and 120 are magnet sensitive
switches 130, such as reed switches, so that each time a magnet 128 passes
a switch 130, the switch momentarily closes (or opens) providing a signal
which is fed by conductors 132 to the electronic package 20. This type of
odometer wheel signal generation is disclosed in U.S. Pat. No. 3,732,625
entitled "Pipeline Pig", issue May 15, 1973.
The use of two odometer wheels provides a redundancy check to achieve an
improved distance measurement employing a method as revealed in U.S. Pat.
No. 3,862,497.
By means of springs 134 the arms 118 and 120 are urged outwardly to
maintain the odometer wheels 124 and 126 in firm engagement with the
interior wall of the pipeline. The method of mounting the odometer wheels
by use of a hinge 114 causes them to be self-centering with respect to the
interior of the pipeline and to thereby accurately position themselves to
engage opposite points on the interior surface of the pipeline so that the
odometer wheels are less likely to slip or otherwise provide an inaccurate
distance measurement.
When a pipeline has been traversed by the caliper pig of the type
disclosed, a record is recorded in the electronic package 120, preferably
in the form of digital signals stored in solid state memory chips. When a
run is completed the operator removes the pig from the pipeline and
removes housing 124, exposing the electronic package. By means of cable
connectors (not shown) communication can readily be established with the
electronic package and the stored record extracted from memory. The stored
record can then be treated by read-out equipment which can be, by example,
in the form of a mini-computer or personal computer. The results of the
caliper pig run can be studied immediately after the run by mobile
equipment on site and thereafter the signals can be more meticulously
analyzed to provide more detail of the results of the run by more
elaborate computer equipment located in an office especially equipped for
detailed analysis of the record.
Referring to FIGS. 9 and 10 an alternate embodiment of the invention is
shown which particularly adapts the pipeline caliper pig to detect bends
and curves in a pipeline. FIGS. 7 and 8, which have been previously
described, show the use of a dual wheel odometer system providing
apparatus to take advantage of the concept of the use of the dual wheel
odometer U.S. Pat. No. 3,862,497 previously mentioned. FIGS. 9 and 10 show
the employment of three odometer wheels. Pivotally affixed to subframe
plate 26, and specifically to brackets 110 extending therefrom, is a hinge
member 136 which, at its rearward portion, is hexagonal in cross-sectional
configuration, the hinge member being pivotally supported by a pin 138.
Pivotally extending from the hinge member 136 are three arms 140, 142 and
144, each pivoted at its inner end about bolts 104A, 142A and 144A,
respectively. At the outer end of the arms are odometer wheels 146, 148
and 150. Springs 134 perform the same function as with reference to FIGS.
7 and 8, that is, they hold the odometer wheels out firmly and yet
yielding against the interior wall of the pipe line 10. Each of the
odometer wheels include means of providing an electrical signal in
proportion to the rotation thereof. One means of accomplishing this is as
set forth in U.S. Pat. No. 3,732,625 wherein each odometer wheel includes
a magnet therein identified by the numbers 152A, 152B and 152C. Rather
than being mounted within each of the odometer wheels the magnets may be
mounted on the wheels' sidewalls.
Affixed to each of the arms is a rotational sensor which may be such as in
the form of a magnet sensitive switch, such as a reed switch, the same
being located within instrument packages 154A, 154B and 154C. Once each
revolution of each of the wheels 146, 148 and 150, or more often if a
greater of magnets is employed on each wheel, an electrical signal is sent
by conductors 132 to the instrument package 20 as shown in FIG. 1.
The odometer wheels, if of the same diameter, will rotate at a different
rate when the caliper pig is traveling in a bend of curve in a pipeline
and the signals generated and stored in the electronic package 20 in this
manner. By means of a proper computer program the stored data can be read
out and analyzed and the completed record can provide information as to
the location of curves and bends in the pipeline. Alternatively, the
signals emanating from the three odometer wheels may be treated by
electronics in package 20 by a self-contained program before the signals
are stored in memory for later retrieval.
The wheels 146, 148 and 150, in addition to their use for indicating curves
and bends, simultaneously function to provide signals employing the
principal of U.S. Pat. Nos. 3,732,625 and 3,862,497 to provide information
as to distance the pig has traveled from the start of a run in a pipeline.
If the pig passes an opening in the side of the pipeline, such as a branch
fitting, valve opening or the like, so that one or more of the wheels
momentarily do not engage the interior wall of the pipeline, the speed of
the rotation of the non-engaging wheel will be reflective of such event
and provide further information for use in correlation of the location of
the pig at specific instances within the pipeline.
It can be seen that instead of three wheels as in FIGS. 9 and 10, the
principle of the invention can be employed using four, five or more
wheels, three being the minimum number necessary to provide signal
information of the traverse of the caliper pig through a pipeline bend or
curve.
The detected bends or curves in a pipeline may be in a horizontal plane or
in a vertical plane, or a combination of both. Curves in a vertical plane
indicate change in elevation, such as when a pipeline turns upwardly to
pass over a hill, or downwardly to pass through a valley or under a river.
Thus, the indications obtained as to bends and curves, when combined with
indications as to the orientation of the pig body assembly relative to the
vertical, provide valuable information which is particularly useful in
correlation with odometer measurements, enabling detected anomolies in the
pipeline interior wall to be pin pointed accurately as to location.
The information obtained by a run of a pig of the present invention through
a pipeline can be analyzed, using an appropriate computer program to
produce displays on a video tube or printed information, either numeric or
graphic. The information derived by the system represented by FIGS. 9 and
10 combined with the means of simultaneously recording the orientation of
the caliper pig relative to the vertical such as by utilizing the concepts
of FIG. 6, in conjunction with the response of the pig to deviations in
the interior wall of the pipeline as illustrated in FIGS. 1 through 5 and
6 provides a highly complete catalog of the interior of a pipeline as the
caliper pig travels from a point of entry to a point of exit.
While the invention has been described with a certain degree of
particularity it is manifest that many changes may be made in the details
of construction and the arrangement of components without departing from
the spirit and scope of this disclosure. It is understood that the
invention is not limited to the embodiments set forth herein for purposes
of exemplification, but is to be limited only by the scope of the attached
claim or claims, including the full range of equivalency to which each
element thereof is entitled.
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